Automatic spark advance device for ignition system



June 18, 1963 c. B. SMALL ETAL 3,0

AUTOMATIC SPARK ADVANCE DEVICE FOR IGNITION SYSTEM Filed July 3, 1961 I 2 Sheets-Sheet 1 INVENTORS. CHARLES B.$MALL GEORGE H.HUFFERD BY HERMAN LANSING VAIL JR no.2 f g/ TORNEY June 18, 1963 c. B. SMALL ETAL AUTOMATIC SPARK ADVANCE DEVICE FOR IGNITION SYSTEM 2 Sheets-Sheet 2 Filed July 3, 1961 FlG.5c

INVENTORS CHARLES MALL GEORGE H. FFERD HERMAN LANSING VAIL JR ATTORNEY FIG.5

United States Patent 3,094,108" AUTOMATIC SPARK ADVANCE DEVICE FOR IGNITION SYSTEM.

Charles B. Small, Willoughby, Herman Lansing Vail, Jr., Shaker Heights, and George H. Hulferd, Lyndhurst; Olii0,assignors;to Clevite Corporation, a corporation of Ohio Filed July 3, 1961, Ser. No. 121,664 17 Claims. (Cl. 123-448) This invention relates to an automatic spark advance device adapted to control in an internal combustion engine ignition system the time of igniting a fuel mixture in relation to the cycle of engine operation.

While the present invention is hereinbelow described with particular reference to a piezoelectric ignition system, it will be appreciated by. those versed in the art that thebasic principles of the invention are of broader application and that the device maybe used in conjunction with other types of voltage sources It has long been recognized that ignition timing in the operating cycle of an internal combustion engine is one of the major factors influencing power output, economy and knocking characteristics of a motor vehicle. To adjust the spark timing for maximum performance engines are today equipped with automatic devices'which cause the spark to be advanced asthe rate of rotation of the crankshaft increases and causes the spark to be retarded as the rate is reduced.

The ignition system predominantly in use today for multicylinder internal combustion engines is a batterycoil ignition system. The ignition system includes a distributor which serves to distribute the voltage at the instant the high tension potential from the ignition coil becomes available to the spark plug. The timer associated with the distributor opens and closes a primary coil circuit. The opening of the primary coil circuit, for instance by means of a breaker lever mechanism, causes a flux collapse in the coil which results in a high potential being generated which must be available, and the availability must coincide with, the closing .of the circuit for immediate transmission through the distributor to the proper spark plug.

Automobile manufacturers presently utilize a vacuum type spark advance mechanism and a centrifugal. spark advance mechanism. In, certain applications the useof vacuum and centrifugal. mechanisms are combined. In the centrifugal type of advance mechanism weights are caused, to move radially outward against springtensionas the engine speed increases. This movement imparts, usually by toggle action, a rotational-motion to a breaker cam, causing the latter. to rotate a number of degrees with respect to thedistributor drive shaft. This has the eflect of causing lobes on the cam to close and open the contact earlier in the cycle so that the voltage is induced and is delivered to the spark plug earlier with respect to the position of the upward moving piston. The generation of high tension potential must of course keep pace with these variations so that the generation of the voltage coincides with the closing of the circuit.

In the ignition system of :the prior art the timer and advance mechanism are constructed to vary and control the generation of flux for proper spark plug firing. In a piezoelectric ignition system a piezoelectric element is compressed under steadily increasing force during one portion of the engine cycle and is relaxed during another part of the cycle to cause peak voltages to \appear across the terminalof the element at the maximum values of squeezing and relaxation. Inasmuch as the practical potential generated by the piezoelectric element as it is squeezed and released can be reached appreciably before the instant the plug should fire and, most importantly,

3,094,108 Patented June 18, 1963 "ice 2' f since these peakvoltages can be stored within certain limits in the element, it will be appreciated that the instant of firing may be varied by electrically disconnecting the spark plug from the electriepotential until the piston has reached the firing position.

Itis therefore the primaryobject of this inventionto provide .an automatic spark advance device which maybe employed in an ignition system characterizedby a voltage source providing a potential prior to thetime that the potential is needed and capable of: retaining the potential until proper firing time, and in which the closing ofthe circuit for spark plug firing is automaticallyvaried in correlative proportion with the rate of rotation of an engine component.

It is another object of this inventionto provide a device of the type aforedescribed which has the attributes of utmost simplicity and in which :the spark advance is established by centrifugal means, obviating the need of cams, springs, and the like commonly required in the prior art.

It is another object of this invention to provide a device in accordance with this invention which by virtue of its simplicity and low manufacturing costcan be used in conjunction with low priced single cylinder engines. Heretofore, the complexity of such devices made the cost prohibitive and, as a consequence, spark advance mechanisms were not available'with and/ or for such engines.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

With reference to the drawings:

FIGURE 1 shows a typical internal combustion engine equipped with a piezoelectric spark ignition system including a spark advance device in accordance with this invention, the engine flywheel and the casing surrounding the flywheel have been removed to facilitate illustration;

FIGURE 2' is a plan view of the inside face otthe spark advance device, portions of the housingv are removed;

FIGURE 3 is a cross-sectional view through the spark advance device taken along line 3-.3 of FIGURE 2;

FIGURES 4 and 5 are views similar to FIGURE 2, each showing a modified spark advance mechanism; and

FIGURES 2a, 4a and 5a illustrate diagrammatically a modification of the bridging conductor shown in FIG URES 2, 4 and 5 respectively.

An aspect of the present invention resides in the provision of an ignition and automatic spark timing system for an internal. combustion engine having a moving component which comprises a piezoelectric element and pressure applying means connected with thepiezoelectric element adapted to apply periodically a. 'force in timed relation with the position of the moving component to the element to generate an electric potential. There is also provided meansresponsive to .a condition of the engine, operably associated with the element to release the potential in timed relation with the position of the moving component, and an. automaticarrangementis operably associated with the element for varying the timed relation of the release correlative to a change in the engine condition.

Refer-ring now to FIGURE 1 of the drawings there is shown an internal eombustionengineofthe type used for lawn mowers and snow plows, however, his to be understood that the .engine is merely illustrative since the invention herein disclosed, is applicable to all. types of internal combustion engines.

As is well known in the art, internal combustion .en-. gines generally have a base 10'including an integral cylinder block 12 into which a spark plug 14 extends.

A gasoline tank 16 is mounted on the engine, and through suitable carburetor means 18 (not described in detail) fuel is supplied to the cylinder or cylinders (not visible) in timed relation to motion of the crankshaft 20 and other engine components. A source of electric potential, such as a piezoelectric spark generator 22, periodically supplies a high voltage electrical spark to each of the one or more cylinders.

The electric circuit between the voltage source 22 and the spark plug .14 is established by electric cables 21 and 23 connected to an automatic spark advance device 40 which is the subject of this invention and is hereinafter described in detail.

A piezoelectric spark generator of the type referred to herein is disclosed and illustrated in co-pending application Serial Number 776,793 filed November 28, 1958, now US. Patent Number 3,009,975 issued November 21, 1961, and assigned to the same assignee as the instant application.

The piezoelectric spark generator 22 contains one or more piezoelectric crystal elements 24 which are periodically squeezed to cause them to generate and hold a high voltage electrical potential until the potential is dischanged, and, thereafter, upon the squeezing action being released, the piezoelectric elements 24 generate another spark potential of opposite polarity.

To effect periodic squeezing and release of the piezoelectric elements 24 an eccentric 26 mounted to camshaft 28 engages a lever arm 30 of the generator 22 so that during each period of camshaft revolution at least one squeezing and releasing action takes place.

It must be noted that the engine illustrated herein is a single cylinder four stroke engine, which requires one spark per every other revolution of the crankshaft 20. Preferably, and conventionally, this firing takes place when the piston is 23 ahead of top dead center. In any event, by mounting the eccentric 26 to the camshaft 28 which rotates at half crankshaft speed, both sparks that are developed during each revolution of the camshaft may effectively be utilized and are sequentially discharged into the cylinder at every other revolution of the crankshaft. On the other hand, if it is necessary to mount the eccentric to the crankshaft so that the eccentric will rotate at crankshaft speed and thus deliver two sparks per revolution of the crankshaft, provision must be made to ground the surplus sparks. The same problem exists in two cycle engines where the cocentric rotates at crankshaft speed, inwhich case one spark per revolution is grounded. A means by which such grounding maybe established is below described.

While various means may be utilized to actuate the piezoelectric spark generator 22, it is essential that the spark firing is closely correlated with the operating cycle of the engine.

The spark advance and distributor unit 40, see FIG- URES 2 and 3, comprises a tubular sleeve 42 mounted to crankshaft 20 for rotating in unison therewith. A radial flange 44 is pressed onto the sleeve 42 and constitutes a circular laminated disc made of non-conductive material. Alternatively, the flange and the disc may be suitably molded in one piece using an insulating plastic. Sandwiched between laminations of the disc 44 is a bridging conductor 46 comprised of resilient conductive spring wire or the like, which is substantially circularly shaped and includes two circumferentially spaced partly enlarged radial end portions 46a, 46b which extend radially with respect to the central axis of the disc and protrude slightly beyond the disc 44. The enlarged end portions 46a, 46b are constructed of conductive material such as copper or the like.

A housing 48 constructed of non-conductive material encloses the rotatable disc 44 to protect the same from dirt particles. The housing 48 includes a base 50 and a cover 52, each of these housing portions are shaped circularly and are formed with a central aperture to slip over an axial support shoulder 54 formed on disc 44. Each of the housing portions forms peripherally a flange 56, 58, which is ridged so that flanges 56 and 58 when facing each other are adapted to tightly fit together.

The base 50 is secured to the engine by means of screws or the like which are not shown, and the base is provided with a plurality of radial ribs 51 to provide a longer leakage path to impede energy dissipation. The base has two circumferentially spaced access openings 60 and 61, a typical opening is shown at 60, see FIG- URE 3, the opening 60 serves to receive one end of the generator cable 21 and opening 61 receives and secures one end of spark plug cable 23. Connected to each conductor cable 21, 23 within each respective opening there is secured a conductive pin 62, 64 respectively, which is partly insulated by a protective wrapping 65 and protrudes through the base 50 into disc compartment 49 adjacent to the respective leading edge 57, 59 of the bridging electrode as shown in FIGURES 2 and 3.

An annular cover 68 is secured to and rotates with the disc 44. The cover consists of a top 68a and a bottom portion 68b, the top portion is spacedly placed adjacent to cover 52 and the bottom portion is spacedly secured adjacent to the opposite side of the base 50. To secure these cover portions 68a, 68b into position, one end of each cover portion is wedged between the tubular sleeve 42 and the support shoulder 54 of the disc 44. Each cover (68a and 68b) serves to retain an annular seal and thrust bearing 70, such as a felt ring, which is lodged between the respective housing member 52 (50) and the respective cover member 68a (68b).

Returning now to the electrical aspects of this invention, it is now seen that the bridging conductor 46 serves as a conductive link between the generator cable 21 and the spark plug cable 23. In order to avoid a spark from flying across the pins 62 and 64, the pins and the cables must be circumferentially spaced apart as aforedescribed and the radial ends 46a, 46b are correspondingly spaced for suitable juxtaposition as hereafter further described. In operation, closing of the firing circuit takes place in the following manner. When the engine is started the disc 44 rotates in unison with the camshaft 28, and the first spark potential will be discharged from the generator 22 through cable 21 across device 40 and into cable 23 when the radial lead portions of the bridging electrode are electrically juxtaposed with pins 62, 64. This process is repeated during each cycle of revolution. By virtue of the high voltage conventionally associated with piezoelectric type ignition systems, an arc of substantial length is generated which causes electrical juxtaposition with the input conductor before actual mechanical juxtaposition takes place.

In order to advance the closing of the firing circuit with respect to the position of the rising piston in the cylinder, the radial rear end 46a of the bridging conductor is mechanically rnoved so as to provide earlier mechanical juxtaposition as well as earlier electrical juxtaposition.

The mechanical advance of the radial rear end portion 46a of the bridging conductor is accomplished by cutting into the disc 44 a radial slot 72 which extends from the periphery of the disc somewhat to near the center of the circular region thereof. A fly weight in the form of a cylindrical disc 74 is slidably disposed within the slot 72 and slidingly abuts at opposite ends against housing members 50, 52. The weight 74 in this position engages the radial portion 460 of the bridging conductor 46 which protrudes out of the disc 44 and extends through the slot 72 slightly beyond the periphery of the disc which constitutes leading edge 59. The slot 72 which defines the passageway in which the weight travels is such that, when the disc 44 is rotated, the weight is urged by centrifugal forces to move radially, and the curvature of the slot causes the weight 74 to move in such -a direction that the weight is in a position to impart a force in the direction of rotation of the disc 44 and deflect the radial portion 46a in that direction. is stationary, it will be appreciated that by angularly defleeting radial portion 46a toward the direction of rotation the circumferential spacing between the two radial portions is changed.

Since the degree of deflection of the radial portion 46a is a function of the speed of rotation, the circumferential spacing changes correlative with respect to the rate of rotation of the crankshaft. At a very low rate of crankshaft revolution, the friction and other stresses associated with deflecting the radial portion 46a will prevent the weight from having any significant effect on the circumferential spacing of the radial portion. As the rate of rotation increases, the force exerted against the radial portion 46a to deflect the same is substantially in direct proportion to the rate of rotation of the crankshaft 20.

The apparatus of the present invention is above-described with reference to a general field of application. However, to meet specific engine specifications it is at times necessary to vary the spacing between the radial portions 46a and 46b of the bridging conductor to suit specific requirements. Thus, while the aforementioned description of the present invention states that the rear radial portion 46a is deflectable, it is understood that the principles of this invention can also be applied to the leading radial end portion 46b, furthermore the deflection of the leading end portion 46b is preferred in certain instances as will hereafter become apparent.

FIGURE 2a illustrates that the invention and more particularly the device embodied in FIGURE 2 may readily be adapted to enable an angular deflection of the leading radial portion 46b of the bridging conductor 46'. This configuration modifies the device only to the extent that the slot 72 is cut into disc 44 adjacent to the leading radial end portion 46b. Weight 74 is disposed within the slot and bears against the inside face of the leading portion 46b to effect a widening of the circumferential distance between the rear 46a and the leading bridging conductor portions.

Essentially, the bridging conductor and mor particularly the rear and leading radial end portions thereof can be circu'm ferentially spaced in a manner that the circumferential distance between the radial portions 46a',| 4617 when the disc is not rotating either equals, is smaller, or greater than the same distance between the conducting pins 62, 64.

The proper spacing is of course dependent upon various engine characteristics well known in the art. When the bridging conductor is constructed so that the radial ends are circumferentially spaced between the generator cable and the spark plug cable so that the distance between the ends is smaller than the comparative distance between the pins 62' and 64', the leading radial end 4611' is preferably deflected.

On the other hand where the distance is greater between the radial portions than between the pins the radially extending rear end portion 46a of the bridging conductor is preferably constructed to be angularly deflectable in the direction of rotation when the disc 44 rotates. Where the aforementioned distance is equal, either the rear or the leading ends may be deflected.

It follows that where the rear portion 46a is constructed for deflection, see FIGURE 2, spark advance is accomplished when the distance between the radial end portions narrows. Contrariwise, where the leading portion 46b of the bridging conductor is deflectable electrical and mechanical juxtaposition is advanced when the circumferential distance between the radial portions widens.

While the aforementioned spacing conditions occur when the disc is not rotating it will be appreciated that at a slow rate of rotation of the engine crankshaft the spacing is slightly changed by virtue of the centrifugal effect on the weights which engage the bridging conductor. A further increase in the rate of rotation causes a Since the other radial portion 46b correlative increase or decrease, depending upon which portion is deflectable, in the circumferential distance between the radial portions of. the bridging conductor. Therefore, when'the engine is operatingat top engine speed the deflectable radialportionis fully advanced and the dis tance between-the radial portions is either at minimum or maximum. It is obvious that the degree of deflection of the radial ends determines whether electrical juxtaposition will occurbefore, during or after mechanical juxtaposition. Ordinarily, in. all. three instances, mechanical and electrical juxtaposition will not coincide when the disc 44 is rotating at a rate of rotation at which the centrifugal force is effective.

FIGURE 2 also illustrates a grounding conductor 76 formed as a circular ring 78 and arranged coaxial with.

the disc 44 and the camshaft 28. A stem 80 extends radially from the ring 78 and is integral therewith. The grounding conductor 76is composed ofa suitable. conductive material and is, in the. same. fashion: as the bridging conductor 46, embedded in the plastic, disc or sandwiched between the lamination. of the disc: 44. The radial stem 80 has a leading edge. 81 which protrudes radially out? ward with respectto the. periphery, of disc 44 to enable electrical juxtaposition. with the, spark generator cable 21 during each cycle of revolution. The grounding conductor 76 can serve one or more functions. One may be to bleed off anycharge from the piezoelectric element 24 which may have remained in the element upon discharging the charge through the bridging conductor 46 to the spark plug. This waste potential is discharged by means of the grounding conductor 76 through the camshaft 28 thereby preventing that any such charge might interfere with the-firing of thespark plug. Another function that this conductor 76' may serve is to. bleed off sequentially any excess spark during each revolutioncf the crankshaft. In such a case, the conductor 76 is placed in the disc 44to be in juxtaposition with cable 21,,

respectively pin 62, during each cycle when the excess spark is generated.

FIGURE 4 illustrates a modified automatic spark mechanism. Herein, again, the disc 45 is formed with a radial slot 82 near the outer periphery of the annular disc 45. Protruding into the slot 82 is. the rear radial portion 47a of the bridging conductor 47 which describes in the slot a bend so that the rear portion 471:: extendsradially with respect to the central axis of the disc and. the outermost edge 59 of the radial. portion protrudes beyond theperiphery of the disc. Care must be takenthat the radial portion in slot 82 has a suflicient degree of flexibility within the slot to perform its function in accordance with this invention. A weight 84 having an elongated. form isfixedly attached to: the, radially extending portion 47, and this weight 84v extends substantially perpendicularthereto. The quantitative properties of the weight depend, of c0urse,.upon numerous factors such as the flexibility-of the bridgingconductor, the degree of circular deflection, the desired speeds, involved andso on.

Thus, when the disc 45 rotates clockwise, the centrifugal forces acting upon the weight 84 cause the latter to circularly deflect the radialportion of the bridging conductor toward the direction of rotation, which has the effect of varying the circumferential spacing of the radial ends of the-bridging conductor correlative with the rate of rotation of the disc, respectively the crankshaft;

In order to avoida flutteringeifect and to prevent vibration of the radial end- 47a that might seriouslyimpair the proper function thereof, a second weight member in the form of a cylindrical disc 86 is secured within the slot, slidably lodged between housing, members 50 and 52 (see FIGURE- 3), and more particularly the cylinder 86 is'wedgedbetween the first weight 84 and the inner wall 88 of the slot 82. When the disc 45 rotates, the second weight 86 is in a wedged position approximately as shown in FIGURE 4. The frictional engagement aris- 7. ing out of this position impedes or prevents any fluttering or vibration of the first weight member 84. The centrifugal effect on the first and the second weight member is cumulative and the quantitative properties of the second weight member must, therefore, carefully be taken into consideration in order to arrive at the desired deflection values.

FIGURE 4a illustrates the embodiment of FIGURE 4, but showing the leading portion 47d of the bridging conductor 4-7 in a deflectable position. For this purpose the slot 82 is suitably arranged to expose the leading radial end 47d and the second weight 86' is wedged between weight 84 and the bridging conductor 47'. The weights cause an angular movement of the leading end 47d when the disc 45 rotates in the direction of rotation whereby the circumferential spacing between the rear and the leading portions 47c, 47d is widened.

The automatic spark advance device disclosed in FIG- URE departs from the embodiments disclosed in FIG- URES 2 and 4 in that, herein, the bridging conductor consists essentially of two separate conductors 90 and 92 which are electrically linked. The conductor 90 is mounted in justaposition with the cable 21 and is sandwiched between laminations of the disc 44a. The conductor 90 is electrically coupled with the conductor 92 leading to the cable 23 by means of a plurality of pins 94 which are extended axially through the disc 44a. One end of the conductor 92 is wound around the pin in a spring-like manner. While the conductor 92 should be of relatively stiff construction the conductor must, nevertheless, be angularly deflectable to vary the circular spacing of the radial end portions 98 and 100 as aforedescribed. A weight 96 is fixedly secured near the center of the circular portion of the conductor 92 and since the spring-like mounting permits the conductor to move in a substantially radial fashion the weight accelerates this movement by virtue of centrifugal forces which affect it when the disc rotates.

FIGURE 5a illustrates the bridging conductor 92 with Weight 96 attached thereto, and more particularly that by a simple reversal of parts it is possible to arrange that the leading radial end portion 98 is deflectable.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

We claim:

1. An ignition and automatic spark timing system for an internal combustion engine having a moving component, comprising, in combination: a piezoelectric element; pressure applying means connected with said piezoelectric element and adapted to apply periodically a force in timed relation with the position of said moving component to said element to generate an electric potential; switch means responsive to a condition of said engine and operably associated with said element to release the potential in timed relation with the position of said moving component; and automatic means controlling said switch means to effect a variable, timed, release of said potential with respect to said moving component.

2. An ignition and automatic spark timing system for an internal combustion engine having a moving component, comprising, in combination: a piezoelectric element; pressure applying means connected with said piezoelectric element and adapted to apply periodically a force in timed relation with the position of said moving component to said element to generate an electric potential; circuit means, including means responsive to a condition of said engine and operably associated with said element to release the potential in timed relation with the position of said moving component; and automatic bridging conductor means electrically linked with said circuit and adapted for varying the timed relation of said release correlative to a Change in said engine condition.

3. An ignition and automatic spark timing system according to claim 2, wherein the automatic bridging conductor means includes centrifugal means operably connected to said engine and constrained to rotate in timed relation to said moving component.

4. An automatic spark advance device for an internal combustion engine having a spark plug and associated with a source of electric potential for producing a voltage in timed relation with the revolution of the engine crankshaft, said spark advance device forming a conducting link in a circuit between the source of electric potential and the spark plug, comprising: a rotatable member; means operatively associating said member with said engine to rotate said member in timed relation with the rotation of said crankshaft; bridging conductor means circumferentially spaced on and mounted to said member to establish a closed circuit between said source of electric potential and said spark plug when said rotatable member rotates; and centrifugal means constrained to rotate with said rotatable member and arranged to vary the circumferential spacing of said bridging conductor means correlative to the rate of rotation of said crankshaft.

5. An automatic spark advance device according to claim 4, wherein said bridging conductor means includes a radially extending end portion circumferentially defiectable toward the direction of rotation, and a weight operably associated with the end portion to deflect said portion when said rotatable member rotates.

6. An automatic spark advance device according to claim 5, wherein said weight is fixedly mounted to said deflectable radial end portion.

7. An automatic spark advance device according to claim 4, wherein said centrifugal means deflects at least a portion of said bridging conductor toward the direction of rotation to vary the circumferential spacing thereof.

8. An automatic spark advance device according to claim 4, including a ground conductor mounted on said rotatable member for periodic circuit cooperation with said source of electric potential when said rotatable member rotates; and means coupled with said ground conductor for connecting the latter electrically to ground.

9. An automatic spark advance device for an internal combustion engine having a spark plug and associated with a source of electric potential for producing a voltage in timed relation with the revolution of the engine crankshaft, said spark advance device forming a conducting link in a circuit between the source of electric potential and the spark plug, comprising: a rotatable disc with a slot formed therein; means operatively associating said disc with said engine to rotate said disc in timed relation with the rate of rotation of said crank shaft; bridging conductor means, including a deflectable portion, circumferentially spaced on and mounted to said disc to establish a closed circuit tbeween said source of electric potential and said spark plug when said rotatable member rotates; a weight movably confined within said slot and located adjacent to said deflectable portion and constrained to rotate with said disc and exerting a force in the direction of rotation against said defiectable portion when said disc rotates.

10. An automatic spark advance device according to claim 9, including a ground conductor mounted on said rotatable member for periodic circuit cooperation with said source of electric potential when said rotatable member rotates; and means coupled with said ground conductor for connecting the latter electrically to ground.

11. An automatic spark advance device for an internal combustion engine having a spark plug and associated with a source of electric potential for producing a voltage in timed relation with the revolution of the engine crankshaft, said spark advance device forming a conducting link in a circuit between the source of electric potential and the spark plug, comprising: a rotatable disc with a slot formed therein; means operatively associating said disc with said engine to rotate said disc in timed relation with the rate of rotation of said crankshaft; bridging conduc tor means, including a deflectable portion, circumferenti-ally spaced on and mounted to said disc to establish a closed circuit between said source of electric potential and said spark plug when said rotatable member rotates; a first weight mounted to said defleotable portion; and a second weight movably confined within said slot and constrained to rotate wi said rotatable disc, said second weight engaging said first weight and exerting a force thereagainst when said disc rotates.

12. An automatic spark advance device for an internal combustion engine ignition system having a source of electric potential for producing a voltage in timed relation with the revolution of the engine crankshaft and being connected to the automatic spark advance device by means of I a stationary input conductor, the system including a spark plug linked to the spark advance device by a stationary output conductor, the latter being circumferentially spaced from the input conductor; compris ing: a rotatable member; means operably associating said member with said engine to rotate said member in timed relation to the rate of rotation of said crankshaft; bridging conductor means mounted to said member, including, a first and a second radially extending end portion circumferentially spaced apart on said member, the circumferential spacing of said end portions being substantially equal to the circumferential spacing of said input and output conductors when said member is not ro tating; and centrifugal means engaging said bridging conductor and effective to vary the circumferential spacing between said end portions when said rotatable member rotates.

13. An automatic spark advance device according to claim 12, wherein said centrifugal means engages one of said radially extending end portions and angularly deflects the engaged end portion in the direction of rotation when said member rotates.

14. An automatic spark advance device for an internal combustion engine ignition system having a source of electric potential for producing a voltage in timed relation with the revolution of the engine crankshaft and being connected to the automatic spark advance device by means of a stationary input conductor, the system including a spark plug linked to the spark advance device by a stationary output conductor, the latter being circumferentially spaced from the input conductor; comprising:

a rotatable member; means operably associating said member with said engine to rotate said member in timed relation to the rate of rotation of said crankshaft; bridging conductor means mounted to said member, including, a rear and a leading radially extending end portion circumferentiall yspaced apart on said member, the circum ferential spacing of said end portions being smaller than the circumferential spacing of said input and output conductors when said member is not rotating; and centrifugal means engaging said bridging conductor and effective to vary the circumferential spacing between said end portions when said rotatable member rotates.

15. An automatic spark advance device according to claim 14, wherein said centrifugal means engages the radially extending leading end portion and angularly deflects the leading end portion in the direction of rotation when said member rotates.

16. An automatic spark advance device for an internal combustion engine ignition system having a source of electric potential for producing a voltage in timed relation with the revolution of the engine crankshaft and being connected to the automatic spark advance device by means of a stationary input conductor, the system including a spark plug linked to the spark advance device by a stationary output conductor, the latter being circumferentially spaced from the input conductor; comprising: a rotatable member; means operably associating said member with said engine to rotate said member in timed relation to the rate of rotation of said crankshaft; bridging conductor means mounted to said member, including a rear and a leading radially extending end portion circumferentially spaced apart on said member, the circumferential spacing of said end portions being greater than the circumferential spacing of said input and output conductors when said member is not rotating; and centrifugal means engaging said bridging conductor and effective to vary the circumferential spacing between said end portions when said rotatable member rotates.

17. An automatic spark advance device according to claim 16, wherein said centrifugal means engages the radially extending rear end portion and angularly deflects the rearend portion in the direction of rotation when said member rotates.

References Cited in the file of this patent UNITED STATES PATENTS 1,059,604 Gaff Apr. 22, 1913 2,814,660 Crownover Nov. 26, 1957 3,009,975 Hufferd et al Nov. 21, 1961 

1. AN IGNITION AND AUTOMATIC SPARK TIMING SYSTEM FOR AN INTERNAL COMBUSTION ENGINE HAVING A MOVING COMPONENT, COMPRISING, IN COMBINATION: A PIEZOELECTRIC ELEMENT; PRESSURE APPLYING MEANS CONNECTED WITH SAID PIEZOELECTRIC ELEMENT AND ADAPTED TO APPLY PERIODICALLY A FORCE IN TIMED RELATION WITH THE POSITION OF SAID MOVING COMPONENT TO SAID ELEMENT TO GENERATE AN ELECTRIC POTENTIAL; SWITCH MEANS RESPONSIVE TO A CONDITION OF SAID ENGINE AND OPERABLY ASSOCIATED WITH SAID ELEMENT TO RELEASE THE POTENTIAL IN TIMED RELATION WITH THE POSITION OF SAID MOVING COMPONENT; AND AUTOMATIC MEANS CONTROLLING SAID SWITCH MEANS TO EFFECT A VARIABLE, TIMED, RELEASE OF SAID POTENTIAL WITH RESPECT TO SAID MOVING COMPONENT. 